International growth offset a continuing drop in domestic passengers as UK airport operator BAA's overall figures inched ahead in August.
Compared to a year previously, the six airports handled 10.7 million passengers, up 0.2%.
BAA recorded a 0.3% increase in European scheduled traffic while long-haul grew 0.6%, compensating for a 5.5% reduction in UK domestic passengers. The reduction in domestic passengers (most notable at London Heathrow, which saw a fall of 13.2%) was due to reduced capacity, said BAA.
Heathrow handled 6.6 million passengers, making it the London airport's busiest-ever August. North Atlantic flights were the strongest performing market, with some individual routes seeing significant increases. The number of passengers on the Montreal run jumped by 50% compared to August 2010, for example, and Detroit rose by 41.9%.
BAA said that the number of passengers using Heathrow in August was 71,000 higher than a year previously and would have been even higher if not for the dampening effect of Hurricane Irene on the American market.
BAA's other London airport, Stansted, continued to see reductions in passenger numbers, dropping 5.1% to 1.98 million due to reductions in airline capacity at the budget carrier-oriented site. However, its August load factor, at 89.3%, was the highest ever.
BAA's three Scottish airports posted strong passenger figures, with Edinburgh up 3% at 955,000, Glasgow rising 5.5% to 682,000 and Aberdeen reporting growth of 6.7% to 276,000.
Southampton saw a 2.4% rise to 188,000.